Concatenated codes are a class of error-correcting codes that combine an inner code and an outer code to provide exponentially decreasing error probability with increasing block length and polynomial-time decoding complexity.
Conventional cable networks include coaxial cable and/or a combination of optic fiber and coaxial cable, the latter of which may be referred to as a hybrid fiber-coaxial (HFC) network.
A cable network may experience sporadic impulse interference, or noise bursts, which may occur at average rate in a range of approximately 10 Hz. Noise bursts durations may be in a range of approximately 20 micro-seconds (μs), which is sufficient to affect one or more symbols of a multi-carrier signal, such as a signal modulated with orthogonal frequency division multiplexing (OFDM). Conventional cable systems utilize single carrier quadrature amplitude modulation (QAM) modulation, which is less affected by impulse noise than a multi-carrier signal, such as signal modulated with OFDM.
Conventional cable systems utilize a concatenated forward error correction (FEC) codes, including a trellis inner code and a Reed-Solomon (RS) outer code.
Conventional cable receivers mitigate impulse noise, or noise bursts, by de-interleaving between trellis decoding and RS decoding. This may not be practical for non-concatenated codes, such as a low-density parity-check (LDPC) code.
In the drawings, the leftmost digit(s) of a reference number identifies the drawing in which the reference number first appears.